Area Forecast Discussion
Issued by NWS Grand Junction, CO

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FXUS65 KGJT 221745
AFDGJT

Area Forecast Discussion
National Weather Service GRAND JUNCTION CO
1145 AM MDT Thu Jun 22 2017

.UPDATE...
Issued at 1145 AM MDT Thu Jun 22 2017

Updating PoPs upward for potential development of thunderstorms
today. Our morning sounding today looks a lot like yesterday`s...which
leads us to believe that we could be in for strong downdrafts
again this afternoon. Unfortunately, trying to pinpoint where
these will happen is near impossible. Analysis of downdraft CAPE
(an indicator of energy available for downdrafts) shows the most
likely area for this will be over the Tavaputs/Bookcliffs/Grand
Mesa area with the threat moving southward toward Moab,

&&

.SHORT TERM...(Today through Friday)
Issued at 247 AM MDT Thu Jun 22 2017

The ridge over the SW U.S. has receded further to the southwest as
a shortwave and weak cold front drop down the front range of the
northern and central rockies. The excessive heat will continue, as
will the heat advisory over southwest and west-central Colorado
and southeast Utah. The passing trough will increase the pressure
gradient and resulting winds aloft and at the surface. The
stronger winds will combine with very hot temperatures and low
humidity to produce critical fire weather conditions over much of
eastern Utah and portions of west-central and southwest Colorado
this afternoon and evening. A modicum of moisture will accompany
the trough which should result in isolated high-based and dry
thunderstorms over mainly the northern half of the area.

The flow aloft will turn more northwesterly Friday with remnants
of the surface front stretching along the front range.
Temperatures will lower and winds will decrease, alleviating some
of the fire weather concerns.

.LONG TERM...(Friday night through Wednesday)
Issued at 247 AM MDT Thu Jun 22 2017

The dry NW flow aloft will continue through the weekend as the
ridge reestablishes over the Great Basin. Monday night and
Tuesday another weak trough will flatten the ridge causing west
winds to increase from Tuesday through Wednesday. There will be a
very slight chance of high-based thunderstorms again and fire
weather concerns will be elevated as well.

&&

.AVIATION...(For the 18Z TAFS through 18Z Friday afternoon)
Issued at 1145 AM MDT Thu Jun 22 2017

Our morning sounding today looks a lot like yesterday`s...which
leads us to believe that we could be in for strong downdrafts (60
kts potentially) again this afternoon. Unfortunately, trying to
pinpoint where these will happen is near impossible, but east
central Utah (Tavaputs to Moab) and west central Colorado
(Bookcliffs to as far south as the Gunnison Basin) looks most
likely. Trying to indicate this threat in the TAFs is difficult,
but added TEMPOS in to show the highest likelihood time frames.
Otherwise, a few showers and thunderstorms here and there. The
smoke noticable in the air tonight is expected to clear late this
afternoon and this evening from north to south. The Four Corners
valleys may see some smoke settle into the valleys. Conditions are
expected to remain VFR over the next 24 hours...except for an
isolated wind gusts that may blow dust up and reduce visibility
temporarily.

&&

.FIRE WEATHER...
Issued at 247 AM MDT Thu Jun 22 2017

Fire Weather conditions are expected to exceed critical levels
for much of eastern Utah and southwest and west-central Colorado
this afternoon and evening. Some stronger winds aloft will move
by this morning. As mixing commences during the afternoon hours,
frequent gusts of 25 mph or more are expected in the areas
previously mentioned. Isolated dry lightning is possible again
this afternoon and early evening, with the with best chance over
the higher peaks along the Continental Divide. Precipitation
chances will drop to near 0 during the weekend.

&&

.HYDROLOGY...
Issued at 247 AM MDT Thu Jun 22 2017

A flood advisory has been issued for the Roaring Fork River in
Aspen as snowmelt and tunnel closures upstream have caused the
river to reach bankfull. This advisory will run through Friday
evening.

A number of streams and creeks also continue to run strong, cold,
and high and will continue to do so through the week. Where water
is running high, river banks may become saturated and unstable.
Lowlands along the rivers may also become inundated with water.
Remember if you are going to raft, kayak or tube on the rivers be
sure to always wear a life jacket.

&&

.GJT WATCHES/WARNINGS/ADVISORIES...
CO...Red Flag Warning until 10 PM MDT this evening for COZ203-207-290-
     292.

     Heat Advisory until 10 PM MDT this evening for COZ006.

UT...Red Flag Warning until 10 PM MDT this evening for UTZ486-487-490-
     491.

     Heat Advisory until 10 PM MDT this evening for UTZ022-027-029.

&&

$$

UPDATE...JAM/MAC
SHORT TERM...CC
LONG TERM...CC
AVIATION...JAM
FIRE WEATHER...CC
HYDROLOGY...CC



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